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ksmbd: fix possible deadlock in smb2_open
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commit 864fb5d upstream.

[ 8743.393379] ======================================================
[ 8743.393385] WARNING: possible circular locking dependency detected
[ 8743.393391] 6.4.0-rc1+ #11 Tainted: G           OE
[ 8743.393397] ------------------------------------------------------
[ 8743.393402] kworker/0:2/12921 is trying to acquire lock:
[ 8743.393408] ffff888127a14460 (sb_writers#8){.+.+}-{0:0}, at: ksmbd_vfs_setxattr+0x3d/0xd0 [ksmbd]
[ 8743.393510]
               but task is already holding lock:
[ 8743.393515] ffff8880360d97f0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: ksmbd_vfs_kern_path_locked+0x181/0x670 [ksmbd]
[ 8743.393618]
               which lock already depends on the new lock.

[ 8743.393623]
               the existing dependency chain (in reverse order) is:
[ 8743.393628]
               -> #1 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}:
[ 8743.393648]        down_write_nested+0x9a/0x1b0
[ 8743.393660]        filename_create+0x128/0x270
[ 8743.393670]        do_mkdirat+0xab/0x1f0
[ 8743.393680]        __x64_sys_mkdir+0x47/0x60
[ 8743.393690]        do_syscall_64+0x5d/0x90
[ 8743.393701]        entry_SYSCALL_64_after_hwframe+0x72/0xdc
[ 8743.393711]
               -> #0 (sb_writers#8){.+.+}-{0:0}:
[ 8743.393728]        __lock_acquire+0x2201/0x3b80
[ 8743.393737]        lock_acquire+0x18f/0x440
[ 8743.393746]        mnt_want_write+0x5f/0x240
[ 8743.393755]        ksmbd_vfs_setxattr+0x3d/0xd0 [ksmbd]
[ 8743.393839]        ksmbd_vfs_set_dos_attrib_xattr+0xcc/0x110 [ksmbd]
[ 8743.393924]        compat_ksmbd_vfs_set_dos_attrib_xattr+0x39/0x50 [ksmbd]
[ 8743.394010]        smb2_open+0x3432/0x3cc0 [ksmbd]
[ 8743.394099]        handle_ksmbd_work+0x2c9/0x7b0 [ksmbd]
[ 8743.394187]        process_one_work+0x65a/0xb30
[ 8743.394198]        worker_thread+0x2cf/0x700
[ 8743.394209]        kthread+0x1ad/0x1f0
[ 8743.394218]        ret_from_fork+0x29/0x50

This patch add mnt_want_write() above parent inode lock and remove
nested mnt_want_write calls in smb2_open().

Fixes: 40b268d ("ksmbd: add mnt_want_write to ksmbd vfs functions")
Cc: stable@vger.kernel.org
Reported-by: Marios Makassikis <mmakassikis@freebox.fr>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@namjaejeon @gregkh
namjaejeon authored and gregkh committed Dec 8, 2023
1 parent 1de3dbd commit 9ab2842
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Showing 5 changed files with 75 additions and 59 deletions.
47 changes: 22 additions & 25 deletions fs/smb/server/smb2pdu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2380,7 +2380,8 @@ static int smb2_set_ea(struct smb2_ea_info *eabuf, unsigned int buf_len,
rc = 0;
} else {
rc = ksmbd_vfs_setxattr(idmap, path, attr_name, value,
le16_to_cpu(eabuf->EaValueLength), 0);
le16_to_cpu(eabuf->EaValueLength),
0, true);
if (rc < 0) {
ksmbd_debug(SMB,
"ksmbd_vfs_setxattr is failed(%d)\n",
Expand Down Expand Up @@ -2443,7 +2444,7 @@ static noinline int smb2_set_stream_name_xattr(const struct path *path,
return -EBADF;
}

rc = ksmbd_vfs_setxattr(idmap, path, xattr_stream_name, NULL, 0, 0);
rc = ksmbd_vfs_setxattr(idmap, path, xattr_stream_name, NULL, 0, 0, false);
if (rc < 0)
pr_err("Failed to store XATTR stream name :%d\n", rc);
return 0;
Expand Down Expand Up @@ -2518,7 +2519,7 @@ static void smb2_new_xattrs(struct ksmbd_tree_connect *tcon, const struct path *
da.flags = XATTR_DOSINFO_ATTRIB | XATTR_DOSINFO_CREATE_TIME |
XATTR_DOSINFO_ITIME;

rc = ksmbd_vfs_set_dos_attrib_xattr(mnt_idmap(path->mnt), path, &da);
rc = ksmbd_vfs_set_dos_attrib_xattr(mnt_idmap(path->mnt), path, &da, false);
if (rc)
ksmbd_debug(SMB, "failed to store file attribute into xattr\n");
}
Expand Down Expand Up @@ -2608,7 +2609,7 @@ static int smb2_create_sd_buffer(struct ksmbd_work *work,
sizeof(struct create_sd_buf_req))
return -EINVAL;
return set_info_sec(work->conn, work->tcon, path, &sd_buf->ntsd,
le32_to_cpu(sd_buf->ccontext.DataLength), true);
le32_to_cpu(sd_buf->ccontext.DataLength), true, false);
}

static void ksmbd_acls_fattr(struct smb_fattr *fattr,
Expand Down Expand Up @@ -3152,7 +3153,8 @@ int smb2_open(struct ksmbd_work *work)
idmap,
&path,
pntsd,
pntsd_size);
pntsd_size,
false);
kfree(pntsd);
if (rc)
pr_err("failed to store ntacl in xattr : %d\n",
Expand Down Expand Up @@ -3228,12 +3230,6 @@ int smb2_open(struct ksmbd_work *work)
if (req->CreateOptions & FILE_DELETE_ON_CLOSE_LE)
ksmbd_fd_set_delete_on_close(fp, file_info);

if (need_truncate) {
rc = smb2_create_truncate(&path);
if (rc)
goto err_out;
}

if (req->CreateContextsOffset) {
struct create_alloc_size_req *az_req;

Expand Down Expand Up @@ -3398,11 +3394,12 @@ int smb2_open(struct ksmbd_work *work)
}

err_out:
if (file_present || created) {
inode_unlock(d_inode(parent_path.dentry));
path_put(&path);
path_put(&parent_path);
}
if (file_present || created)
ksmbd_vfs_kern_path_unlock(&parent_path, &path);

if (fp && need_truncate)
rc = smb2_create_truncate(&fp->filp->f_path);

ksmbd_revert_fsids(work);
err_out1:
if (!rc) {
Expand Down Expand Up @@ -5537,7 +5534,7 @@ static int smb2_rename(struct ksmbd_work *work,
rc = ksmbd_vfs_setxattr(file_mnt_idmap(fp->filp),
&fp->filp->f_path,
xattr_stream_name,
NULL, 0, 0);
NULL, 0, 0, true);
if (rc < 0) {
pr_err("failed to store stream name in xattr: %d\n",
rc);
Expand Down Expand Up @@ -5630,11 +5627,9 @@ static int smb2_create_link(struct ksmbd_work *work,
if (rc)
rc = -EINVAL;
out:
if (file_present) {
inode_unlock(d_inode(parent_path.dentry));
path_put(&path);
path_put(&parent_path);
}
if (file_present)
ksmbd_vfs_kern_path_unlock(&parent_path, &path);

if (!IS_ERR(link_name))
kfree(link_name);
kfree(pathname);
Expand Down Expand Up @@ -5701,7 +5696,8 @@ static int set_file_basic_info(struct ksmbd_file *fp,
da.flags = XATTR_DOSINFO_ATTRIB | XATTR_DOSINFO_CREATE_TIME |
XATTR_DOSINFO_ITIME;

rc = ksmbd_vfs_set_dos_attrib_xattr(idmap, &filp->f_path, &da);
rc = ksmbd_vfs_set_dos_attrib_xattr(idmap, &filp->f_path, &da,
true);
if (rc)
ksmbd_debug(SMB,
"failed to restore file attribute in EA\n");
Expand Down Expand Up @@ -6013,7 +6009,7 @@ static int smb2_set_info_sec(struct ksmbd_file *fp, int addition_info,
fp->saccess |= FILE_SHARE_DELETE_LE;

return set_info_sec(fp->conn, fp->tcon, &fp->filp->f_path, pntsd,
buf_len, false);
buf_len, false, true);
}

/**
Expand Down Expand Up @@ -7582,7 +7578,8 @@ static inline int fsctl_set_sparse(struct ksmbd_work *work, u64 id,

da.attr = le32_to_cpu(fp->f_ci->m_fattr);
ret = ksmbd_vfs_set_dos_attrib_xattr(idmap,
&fp->filp->f_path, &da);
&fp->filp->f_path,
&da, true);
if (ret)
fp->f_ci->m_fattr = old_fattr;
}
Expand Down
7 changes: 4 additions & 3 deletions fs/smb/server/smbacl.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1185,7 +1185,7 @@ int smb_inherit_dacl(struct ksmbd_conn *conn,
pntsd_size += sizeof(struct smb_acl) + nt_size;
}

ksmbd_vfs_set_sd_xattr(conn, idmap, path, pntsd, pntsd_size);
ksmbd_vfs_set_sd_xattr(conn, idmap, path, pntsd, pntsd_size, false);
kfree(pntsd);
}

Expand Down Expand Up @@ -1377,7 +1377,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,

int set_info_sec(struct ksmbd_conn *conn, struct ksmbd_tree_connect *tcon,
const struct path *path, struct smb_ntsd *pntsd, int ntsd_len,
bool type_check)
bool type_check, bool get_write)
{
int rc;
struct smb_fattr fattr = {{0}};
Expand Down Expand Up @@ -1437,7 +1437,8 @@ int set_info_sec(struct ksmbd_conn *conn, struct ksmbd_tree_connect *tcon,
if (test_share_config_flag(tcon->share_conf, KSMBD_SHARE_FLAG_ACL_XATTR)) {
/* Update WinACL in xattr */
ksmbd_vfs_remove_sd_xattrs(idmap, path);
ksmbd_vfs_set_sd_xattr(conn, idmap, path, pntsd, ntsd_len);
ksmbd_vfs_set_sd_xattr(conn, idmap, path, pntsd, ntsd_len,
get_write);
}

out:
Expand Down
2 changes: 1 addition & 1 deletion fs/smb/server/smbacl.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -207,7 +207,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
__le32 *pdaccess, int uid);
int set_info_sec(struct ksmbd_conn *conn, struct ksmbd_tree_connect *tcon,
const struct path *path, struct smb_ntsd *pntsd, int ntsd_len,
bool type_check);
bool type_check, bool get_write);
void id_to_sid(unsigned int cid, uint sidtype, struct smb_sid *ssid);
void ksmbd_init_domain(u32 *sub_auth);

Expand Down
68 changes: 41 additions & 27 deletions fs/smb/server/vfs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -97,6 +97,13 @@ static int ksmbd_vfs_path_lookup_locked(struct ksmbd_share_config *share_conf,
return -ENOENT;
}

err = mnt_want_write(parent_path->mnt);
if (err) {
path_put(parent_path);
putname(filename);
return -ENOENT;
}

inode_lock_nested(parent_path->dentry->d_inode, I_MUTEX_PARENT);
d = lookup_one_qstr_excl(&last, parent_path->dentry, 0);
if (IS_ERR(d))
Expand All @@ -123,6 +130,7 @@ static int ksmbd_vfs_path_lookup_locked(struct ksmbd_share_config *share_conf,

err_out:
inode_unlock(d_inode(parent_path->dentry));
mnt_drop_write(parent_path->mnt);
path_put(parent_path);
putname(filename);
return -ENOENT;
Expand Down Expand Up @@ -451,7 +459,8 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
fp->stream.name,
(void *)stream_buf,
size,
0);
0,
true);
if (err < 0)
goto out;

Expand Down Expand Up @@ -593,10 +602,6 @@ int ksmbd_vfs_remove_file(struct ksmbd_work *work, const struct path *path)
goto out_err;
}

err = mnt_want_write(path->mnt);
if (err)
goto out_err;

idmap = mnt_idmap(path->mnt);
if (S_ISDIR(d_inode(path->dentry)->i_mode)) {
err = vfs_rmdir(idmap, d_inode(parent), path->dentry);
Expand All @@ -607,7 +612,6 @@ int ksmbd_vfs_remove_file(struct ksmbd_work *work, const struct path *path)
if (err)
ksmbd_debug(VFS, "unlink failed, err %d\n", err);
}
mnt_drop_write(path->mnt);

out_err:
ksmbd_revert_fsids(work);
Expand Down Expand Up @@ -907,18 +911,22 @@ ssize_t ksmbd_vfs_getxattr(struct mnt_idmap *idmap,
* @attr_value: xattr value to set
* @attr_size: size of xattr value
* @flags: destination buffer length
* @get_write: get write access to a mount
*
* Return: 0 on success, otherwise error
*/
int ksmbd_vfs_setxattr(struct mnt_idmap *idmap,
const struct path *path, const char *attr_name,
void *attr_value, size_t attr_size, int flags)
void *attr_value, size_t attr_size, int flags,
bool get_write)
{
int err;

err = mnt_want_write(path->mnt);
if (err)
return err;
if (get_write == true) {
err = mnt_want_write(path->mnt);
if (err)
return err;
}

err = vfs_setxattr(idmap,
path->dentry,
Expand All @@ -928,7 +936,8 @@ int ksmbd_vfs_setxattr(struct mnt_idmap *idmap,
flags);
if (err)
ksmbd_debug(VFS, "setxattr failed, err %d\n", err);
mnt_drop_write(path->mnt);
if (get_write == true)
mnt_drop_write(path->mnt);
return err;
}

Expand Down Expand Up @@ -1251,6 +1260,13 @@ int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *name,
}

if (!err) {
err = mnt_want_write(parent_path->mnt);
if (err) {
path_put(path);
path_put(parent_path);
return err;
}

err = ksmbd_vfs_lock_parent(parent_path->dentry, path->dentry);
if (err) {
path_put(path);
Expand All @@ -1260,6 +1276,14 @@ int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *name,
return err;
}

void ksmbd_vfs_kern_path_unlock(struct path *parent_path, struct path *path)
{
inode_unlock(d_inode(parent_path->dentry));
mnt_drop_write(parent_path->mnt);
path_put(path);
path_put(parent_path);
}

struct dentry *ksmbd_vfs_kern_path_create(struct ksmbd_work *work,
const char *name,
unsigned int flags,
Expand Down Expand Up @@ -1414,7 +1438,8 @@ static struct xattr_smb_acl *ksmbd_vfs_make_xattr_posix_acl(struct mnt_idmap *id
int ksmbd_vfs_set_sd_xattr(struct ksmbd_conn *conn,
struct mnt_idmap *idmap,
const struct path *path,
struct smb_ntsd *pntsd, int len)
struct smb_ntsd *pntsd, int len,
bool get_write)
{
int rc;
struct ndr sd_ndr = {0}, acl_ndr = {0};
Expand Down Expand Up @@ -1474,7 +1499,7 @@ int ksmbd_vfs_set_sd_xattr(struct ksmbd_conn *conn,

rc = ksmbd_vfs_setxattr(idmap, path,
XATTR_NAME_SD, sd_ndr.data,
sd_ndr.offset, 0);
sd_ndr.offset, 0, get_write);
if (rc < 0)
pr_err("Failed to store XATTR ntacl :%d\n", rc);

Expand Down Expand Up @@ -1563,7 +1588,8 @@ int ksmbd_vfs_get_sd_xattr(struct ksmbd_conn *conn,

int ksmbd_vfs_set_dos_attrib_xattr(struct mnt_idmap *idmap,
const struct path *path,
struct xattr_dos_attrib *da)
struct xattr_dos_attrib *da,
bool get_write)
{
struct ndr n;
int err;
Expand All @@ -1573,7 +1599,7 @@ int ksmbd_vfs_set_dos_attrib_xattr(struct mnt_idmap *idmap,
return err;

err = ksmbd_vfs_setxattr(idmap, path, XATTR_NAME_DOS_ATTRIBUTE,
(void *)n.data, n.offset, 0);
(void *)n.data, n.offset, 0, get_write);
if (err)
ksmbd_debug(SMB, "failed to store dos attribute in xattr\n");
kfree(n.data);
Expand Down Expand Up @@ -1845,10 +1871,6 @@ int ksmbd_vfs_set_init_posix_acl(struct mnt_idmap *idmap,
}
posix_state_to_acl(&acl_state, acls->a_entries);

rc = mnt_want_write(path->mnt);
if (rc)
goto out_err;

rc = set_posix_acl(idmap, dentry, ACL_TYPE_ACCESS, acls);
if (rc < 0)
ksmbd_debug(SMB, "Set posix acl(ACL_TYPE_ACCESS) failed, rc : %d\n",
Expand All @@ -1860,9 +1882,7 @@ int ksmbd_vfs_set_init_posix_acl(struct mnt_idmap *idmap,
ksmbd_debug(SMB, "Set posix acl(ACL_TYPE_DEFAULT) failed, rc : %d\n",
rc);
}
mnt_drop_write(path->mnt);

out_err:
free_acl_state(&acl_state);
posix_acl_release(acls);
return rc;
Expand Down Expand Up @@ -1892,10 +1912,6 @@ int ksmbd_vfs_inherit_posix_acl(struct mnt_idmap *idmap,
}
}

rc = mnt_want_write(path->mnt);
if (rc)
goto out_err;

rc = set_posix_acl(idmap, dentry, ACL_TYPE_ACCESS, acls);
if (rc < 0)
ksmbd_debug(SMB, "Set posix acl(ACL_TYPE_ACCESS) failed, rc : %d\n",
Expand All @@ -1907,9 +1923,7 @@ int ksmbd_vfs_inherit_posix_acl(struct mnt_idmap *idmap,
ksmbd_debug(SMB, "Set posix acl(ACL_TYPE_DEFAULT) failed, rc : %d\n",
rc);
}
mnt_drop_write(path->mnt);

out_err:
posix_acl_release(acls);
return rc;
}
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